Near-eye display optical waveguide and near-eye display device

Abstract

The application provides a near-eye display optical waveguide and a near-eye display device. The near-eye display optical waveguide comprises a waveguide substrate, at least one in-coupling optical element and at least one out-coupling grating. The out-coupling grating comprises a first diffraction region, which comprises a plurality of basic unit cells arranged periodically in at least one periodic direction parallel to the waveguide substrate; each basic unit cell comprises at least one sub-wavelength optical structure; the sub-wavelength optical structures of at least two basic unit cells of the first diffraction region are of the same shape, and the angles between the rotation axes of the sub-wavelength optical structures of the at least two basic unit cells and the same periodic direction are different; the rotation axis is a straight line connecting any two points that do not coincide with each other on the edge of the normal projection of the sub-wavelength optical structure in a projection plane, and the projection plane is perpendicular to the stacking direction. The energy loss is reduced, the energy utilization rate is improved, and the display field uniformity is improved.

Description

Technical Field

[0001] This application relates to the field of optical technology, and in particular to a near-eye display optical waveguide and a near-eye display device. Background Technology

[0002] In recent years, near-eye display technology has received widespread attention and developed rapidly. As a promising next-generation display system, virtual reality (VR) and augmented reality (AR) technologies offer humanity entirely new ways to perceive the world. VR and AR devices can establish a revolutionary new interactive mode between the observer, the displayed image, and the real world. VR technology combines near-eye display devices with digital image display devices, and through a sufficiently large field of view (FOV) design, it enables users to obtain an immersive, all-around viewing experience without being physically present in the actual environment. AR technology, on the other hand, uses see-through near-eye display devices to overlay virtual images onto the real world, greatly enriching the amount of information people observe in the world per unit of time and enhancing the perceptual dimension of user interaction with the real world. Some VR and AR devices are also gradually demonstrating great application value and development prospects in many fields such as education, healthcare, transportation, engineering, and gaming.

[0003] In the design and manufacturing of VR and AR devices, related technologies can improve the display performance of diffractive waveguides to some extent, but they result in significant energy loss and low energy utilization. Summary of the Invention

[0004] This application provides an improved near-eye display waveguide and near-eye display device.

[0005] This application provides a near-eye display waveguide, comprising: a waveguide substrate, at least one coupling optical element, and at least one coupling grating. The coupling optical element and the coupling grating are disposed on the waveguide substrate, and the coupling grating and the waveguide substrate are stacked in a stacking direction. The coupling optical element is used to couple a light beam into the waveguide substrate; the coupling grating is used to couple the light beam out of the waveguide substrate. The coupling grating includes a first diffraction region, which includes a plurality of basic unit elements periodically arranged in at least one periodic direction parallel to the waveguide substrate. Each basic unit element includes at least one subwavelength optical structure. The subwavelength optical structures of at least two basic unit elements in the first diffraction region have the same shape, and the angles between the rotation axes of the subwavelength optical structures of the at least two basic unit elements and the same periodic direction are different. The rotation axis is a straight line connecting any two non-coincident points on the edge of the orthographic projection of the subwavelength optical structure in a projection plane, and the projection plane is perpendicular to the stacking direction.

[0006] Optionally, the at least one periodic direction includes a first periodic direction in which the angle between the rotation axis of the subwavelength optical structure of at least two of the basic unit elements and the first periodic direction is different.

[0007] Optionally, in the first periodic direction, the angle between the rotation axis of the subwavelength optical structure of two adjacent basic units and the first periodic direction is different.

[0008] Optionally, in the first periodic direction, the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the first periodic direction gradually changes sequentially in the first periodic direction.

[0009] Optionally, the at least one periodic direction includes a second periodic direction intersecting the first periodic direction, wherein the angle between the rotation axis of the subwavelength optical structure of at least two of the basic unit elements and the second periodic direction is different.

[0010] Optionally, in the second periodic direction, the angle between the rotation axis of the subwavelength optical structure of two adjacent basic units and the second periodic direction is different.

[0011] Optionally, in the second periodic direction, the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the second periodic direction gradually changes sequentially in the second periodic direction.

[0012] Optionally, the at least one periodic direction includes a second periodic direction, in which the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the second periodic direction remains unchanged.

[0013] Optionally, the plurality of basic unit elements in the first diffraction region are arranged in an odd-symmetric or even-symmetric manner with respect to at least one axis of symmetry, wherein the at least one axis of symmetry is parallel to the at least one periodic direction.

[0014] Optionally, the rotation axes of the subwavelength optical structures of the plurality of basic unit elements located on one side of the at least one axis of symmetry may be the same or different from the angles between them and the same periodic direction.

[0015] Optionally, the plurality of basic unit elements in the first diffraction region are arranged in a centrally symmetrical manner with respect to at least one symmetrical point in the first diffraction region.

[0016] Optionally, the planar coordinates of at least two reference points of the basic unit element corresponding to different included angles in the projection plane have the same functional relationship with the included angle corresponding to the basic unit element, and the reference point is any point on the orthographic projection of the subwavelength optical structure of the basic unit element in the projection plane.

[0017] Optionally, the at least one periodic direction includes a first periodic direction, in which the included angles corresponding to at least two of the basic unit elements are different, and the included angles corresponding to the at least two of the basic unit elements have a first univariate functional relationship with the planar coordinates of the corresponding reference point in the first periodic direction.

[0018] Optionally, the at least one periodic direction includes a second periodic direction that intersects with the first periodic direction. In the second periodic direction, the included angles corresponding to at least two of the basic unit elements are different, and the included angles corresponding to the at least two of the basic unit elements have a second univariate functional relationship with the planar coordinates of the corresponding reference point in the second periodic direction.

[0019] Optionally, the at least one periodic direction includes a first periodic direction and a second periodic direction intersecting the first periodic direction. In the first periodic direction, the included angles corresponding to at least two of the basic unit elements are different. In the second periodic direction, the included angles corresponding to at least two of the basic unit elements are different. In a plane formed by axes parallel to the first periodic direction and parallel to the second periodic direction, the included angles of these corresponding basic unit elements with different included angles relative to the same periodic direction and the plane coordinates of the corresponding reference point have a binary function relationship.

[0020] Optionally, the functional relationship is a distribution function relationship or a piecewise function relationship.

[0021] Optionally, the subwavelength optical structure is a symmetrical structure.

[0022] Optionally, the subwavelength optical structure includes a columnar structure, a conical structure, or a truncated structure.

[0023] Optionally, the cross-section of the subwavelength optical structure is a regular shape formed by straight edges, or by curved edges, or by both straight and curved edges.

[0024] Optionally, the surface of the waveguide substrate can be any one of a plane, a convex surface, a concave surface, an aspherical surface, or a freeform surface.

[0025] Optionally, the first diffraction region is a regular or irregular region enclosed by straight edges, or by curved edges, or by both straight and curved edges.

[0026] Optionally, the coupling grating further includes a second diffraction region, the second diffraction region including diffraction unit elements arranged in at least one arrangement direction, the subwavelength optical structure of the diffraction unit elements of the second diffraction region having the same or different shape as the subwavelength optical structure of the basic unit element of the first diffraction region, and the rotation axis of the subwavelength optical structure of the diffraction unit elements of the second diffraction region having the same angle with the same arrangement direction.

[0027] Optionally, the first diffraction region includes a first sub-diffraction region and a second sub-diffraction region. The rotation axes of the subwavelength optical structures of the plurality of basic units in the first sub-diffraction region are at the same angle to the same periodic direction. The rotation axes of the subwavelength optical structures of the plurality of basic units in the second sub-diffraction region are at the same angle to the same periodic direction. The angles of the sub-diffraction regions corresponding to the plurality of basic units in the first sub-diffraction region and the plurality of basic units in the second sub-diffraction region are different relative to the same periodic direction.

[0028] Optionally, the first sub-diffraction region and the second sub-diffraction region are symmetrically arranged with respect to a regional symmetry axis, which is parallel to one of the periodic directions, wherein the regional symmetry axis is the symmetry axis between the first sub-diffraction region and the second sub-diffraction region.

[0029] This application embodiment also provides a near-eye display device, including:

[0030] Projection device; and

[0031] In any of the above embodiments, the near-eye display waveguide has the projection device disposed on one side of the waveguide; the coupling optical element of the waveguide is used to couple the light beam containing image information emitted by the projection device into the waveguide substrate of the waveguide.

[0032] The near-eye display waveguide of this application embodiment includes a coupling grating comprising a first diffraction region. The subwavelength optical structures of at least two basic unit elements of the first diffraction region have the same shape, and the angles between the rotation axes of the at least two basic unit elements and the same periodic direction are different, thereby reducing energy loss and improving energy utilization and display field uniformity. Attached Figure Description

[0033] Figure 1 The diagram shown is a structural schematic of one embodiment of the near-eye display device of this application.

[0034] Figure 2 The diagram shown is a structural schematic of another embodiment of the near-eye display device of this application.

[0035] Figure 3 The diagram shown is a structural schematic of another embodiment of the near-eye display device of this application.

[0036] Figure 4 The diagram shown is a structural schematic of another embodiment of the near-eye display device of this application.

[0037] Figure 5 As shown Figure 1 The diagram shows a top view of the near-eye display waveguide structure.

[0038] Figure 6 As shown Figure 5 The diagram shows a structural schematic of one embodiment of a near-eye display waveguide.

[0039] Figure 7 As shown Figure 5 The diagram shows a structural schematic of another embodiment of the near-eye display waveguide.

[0040] Figure 8 As shown Figure 5 The diagram shows a structural schematic of another embodiment of the near-eye display waveguide.

[0041] Figure 9 As shown Figure 5 A schematic diagram of another embodiment of the near-eye display waveguide is shown.

[0042] Figure 10 As shown Figure 5 The diagram shows a structural schematic of another embodiment of the near-eye display waveguide.

[0043] Figure 11 The figure shown is a simulation diagram of the energy distribution in the display field of a near-eye display device of a related technology.

[0044] Figure 12 As shown Figure 5 The image shown is a simulation diagram of the energy distribution in the field of view displayed by a near-eye display device. Detailed Implementation

[0045] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0046] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the application. Unless otherwise defined, the technical or scientific terms used in this application should be understood in their ordinary sense by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. "A plurality" or "several" indicates at least two. Unless otherwise stated, terms such as "front," "rear," "lower," and / or "upper" are for ease of description only and are not limited to a location or spatial orientation. Terms such as "comprising" or "including" mean that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect.

[0047] The singular forms “a,” “the,” and “the” used in this application specification and appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0048] The terms used in this article include near-eye display, unit element, and basic unit element. Near-eye display refers to displaying an image source within the near field of view of the human eye using devices such as light sources, light guides, and display panels. Unit element: A two-dimensional periodic pattern is formed by the seamless and non-overlapping regular arrangement of a basic graphic unit; this basic graphic unit is called a unit element. Basic unit element: For the same two-dimensional periodic pattern, there are multiple ways to choose the unit element; the unit element with the smallest area is called the basic unit element.

[0049] This application provides a near-eye display waveguide and a near-eye display device. The near-eye display waveguide includes a waveguide substrate, at least one coupling optical element, and at least one coupling grating. The coupling optical element and the coupling grating are disposed on the waveguide substrate, and the coupling grating and the waveguide substrate are stacked in a stacking direction. The coupling optical element is used to couple a light beam into the waveguide substrate; the coupling grating is used to couple a light beam out of the waveguide substrate. The coupling grating includes a first diffraction region, which includes a plurality of basic unit elements periodically arranged in at least one periodic direction parallel to the waveguide substrate. Each basic unit element includes at least one subwavelength optical structure. The subwavelength optical structures of at least two basic unit elements in the first diffraction region have the same shape, and the angle α between the rotation axis of the subwavelength optical structure of the at least two basic unit elements and the same periodic direction is different. The rotation axis is a straight line connecting any two non-coincident points on the edge of the orthographic projection of the subwavelength optical structure in the projection plane, and the projection plane is perpendicular to the stacking direction.

[0050] The near-eye display waveguide of this application embodiment includes a coupling grating comprising a first diffraction region. The subwavelength optical structures of at least two basic unit elements of the first diffraction region have the same shape, and the angle α between the rotation axis of the subwavelength optical structures of at least two basic unit elements and the same periodic direction is different, thereby reducing energy loss and improving energy utilization and display field uniformity.

[0051] This application provides a near-eye display waveguide and a near-eye display device. The near-eye display waveguide and near-eye display device of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0052] In some embodiments, the near-eye display device 10 includes one of augmented reality glasses, an augmented reality helmet, a head-mounted display, and a projection display device. Any of the above near-eye display devices 10 not only meets the user's wearability requirements but also satisfies requirements such as lightweight design and miniaturization.

[0053] like Figure 1As shown, the near-eye display device 10 includes a projection device 100 and a near-eye display waveguide 200, with the projection device 100 disposed on one side of the near-eye display waveguide 200. Near-eye display refers to displaying an image source within the near field of view of the human eye using devices such as a light source, a light guide, and a display panel. The projection device 100 is used to emit a light beam containing image information to the near-eye display waveguide 200. The near-eye display waveguide 200 is used to couple the light beam containing image information emitted by the projection device 100 into, transmit, and couple out to the human eye 300. In some embodiments, the projection device 100 may be a projection optical engine or a projector.

[0054] In some embodiments, the near-eye display waveguide 200 includes a waveguide substrate 201, at least one coupled optical element 202, and at least one coupled-out grating 203, wherein the coupled optical element 202 and the coupled-out grating 203 are disposed on the waveguide substrate 201. The coupled-out grating 203 and the waveguide substrate 201 are stacked in a stacking direction. The coupled optical element 202 is used to couple a light beam containing image information emitted by the projection device 100 into the waveguide substrate 201. The coupled-out grating 203 is used to couple the light beam out of the waveguide substrate 201 and into the human eye 300.

[0055] In some embodiments, the projection device 100 and the human eye 300 are located on the same side or different sides of the near-eye display light waveguide 200. In some embodiments, the projection device 100 and the coupled optical element 202 are located on the same side or different sides of the waveguide substrate 201. In some embodiments, the coupled optical element 202 and the coupled-out grating 203 are located on the same side or different sides of the waveguide substrate 201.

[0056] exist Figure 1 In the illustrated embodiment, the projection device 100 and the human eye 300 are located on the same side of the near-eye display light waveguide 200. The coupling optical element 202 and the coupling grating 203 are located on the same side of the waveguide substrate 201. The projection device 100 and the coupling optical element 202 are located on the same side of the waveguide substrate 201. The light beam containing image information emitted by the projection device 100 is transmitted and coupled into the waveguide substrate 201 under the action of the coupling optical element 202, and is transmitted losslessly along the positive X-axis direction of the waveguide substrate 201 by total internal reflection. When the light beam is transmitted to the coupling grating 203, a two-dimensional exit pupil expansion occurs under the action of the coupling grating 203, and the coupled light rays are transmitted into the human eye 300. In this process, the two-dimensional exit pupil expansion means that the display pupil range of the light emitted by the image source is expanded in the two-dimensional direction axis after being transmitted in the near-eye display light waveguide 200.

[0057] exist Figure 2 In the illustrated embodiment, with Figure 1The embodiments shown are similar, with the main difference being that the projection device 110 and the coupling optical element 212 are located on different sides of the waveguide substrate 211. The light beam containing image information emitted by the projection device 110 is reflected and coupled into the waveguide substrate 211 by the coupling optical element 212, and then transmitted losslessly along the positive X-axis direction of the waveguide substrate 211 via total internal reflection. When the light beam is transmitted to the output grating 213, it undergoes two-dimensional exit pupil expansion under the action of the output grating 213, and the coupled light rays are reflected into the human eye 310.

[0058] exist Figure 3 In the illustrated embodiment, with Figure 1 The embodiments shown are similar, with the main difference being that the coupling optical element 222 and the coupling grating 223 are located on different sides of the waveguide substrate 221. The projection device 120 and the coupling optical element 222 are located on the same side of the waveguide substrate 221. The beam of light containing image information emitted by the projection device 120 is transmitted through the coupling waveguide substrate 221 under the action of the coupling optical element 222 and is transmitted losslessly along the positive X-axis direction of the waveguide substrate 221 via total internal reflection. When the beam of light is transmitted to the coupling grating 223, it undergoes two-dimensional exit pupil expansion under the action of the coupling grating 223, and the coupled light rays are reflected into the human eye 320.

[0059] exist Figure 4 In the illustrated embodiment, with Figure 1 The embodiments shown are similar, with the main difference being that the coupling optical element 232 and the coupling grating 233 are located on different sides of the waveguide substrate 231. The projection device 130 and the coupling optical element 232 are located on different sides of the waveguide substrate 231. The light beam containing image information emitted by the projection device 130 is reflected into the waveguide substrate 231 by the coupling optical element 232 and transmitted losslessly along the positive X-axis direction in the waveguide substrate 231 via total internal reflection. When the light beam reaches the coupling grating 233, it undergoes two-dimensional exit pupil expansion under the action of the coupling grating 233, while the coupled light rays are transmitted into the human eye 330.

[0060] It should be noted that, Figures 1 to 4 The image shows only four configurations of the near-eye display device 10 provided in this application. Depending on the actual product requirements, the projection device 100, the coupled optical element 202, the coupled grating 203, and the human eye 300 can be configured on any side of the waveguide substrate 201, but are not limited to these configurations.

[0061] exist Figure 5In the illustrated embodiment, the coupling optical element 202 and the coupling grating 203 are offset on the near-eye display waveguide 200. One or more coupling optical elements 202 may be provided. One or more coupling gratings 203 may be provided. In some specific embodiments, a group or more other grating structures may be provided around the coupling optical element 202 and the coupling grating 203, which is not limited in this application.

[0062] In some embodiments, the coupling optical element 202 may be any one of a one-dimensional straight-tooth grating, a blazed grating, or a tilted grating with surface relief characteristics. In other embodiments, the coupling optical element 202 may also be any one of a photonic crystal, a metamaterial, or a metasurface. In still other embodiments, the coupling optical element 202 may be a grating with other optical structures. No limitation is made in this application.

[0063] exist Figure 5 In the illustrated embodiment, the coupling grating 203 includes a first diffraction region 204. At least one first diffraction region 204 may be provided. One or more first diffraction regions 204 may be provided. The first diffraction region 204 includes a plurality of basic unit cells 205 periodically arranged in at least one periodic direction parallel to the waveguide substrate 201. The at least one periodic direction parallel to the waveguide substrate 201 may be an X-axis periodic direction or a Y-axis periodic direction. The X-axis periodic direction and the Y-axis periodic direction are intersecting or have a specific included angle α. The plurality of basic unit cells 205 are periodically arranged in the X-axis periodic direction and / or the Y-axis periodic direction.

[0064] like Figure 6 As shown, each basic unit cell 205 includes at least one subwavelength optical structure 206. Each basic unit cell 205 has one subwavelength optical structure 206 or has multiple subwavelength optical structures 206 (a group of subwavelength optical structures). In this embodiment, each basic unit cell 205 includes a subwavelength optical structure. The subwavelength optical structures 206 of at least two basic unit cells 205 in the first diffraction region 204 have the same shape, and the rotation axis of the subwavelength optical structures of the at least two basic unit cells 205 make an angle α with at least one periodic direction in which the basic unit cells 205 are arranged on the surface of the waveguide substrate 201. The angle α between the rotation axis L and the same periodic direction is different. Wherein, the rotation axis L is a straight line connecting any two non-coincident points on the edge of the orthographic projection of the subwavelength optical structure 206 in the projection plane, and the projection plane is perpendicular to the stacking direction. The subwavelength optical structure 206 has at least one axis of symmetry, and its cross-sectional shape is mirror-symmetric or anti-symmetric with respect to the axis of symmetry, and the axis of symmetry is defined as the rotation axis.

[0065] It should be noted that regardless of whether the basic unit element 205 has one or more subwavelength optical structures, its corresponding rotation axis L is a straight line between any two non-coincident points on the edge of the orthographic projection in the projection plane. There are multiple such rotation axes L.

[0066] In the above scheme, the coupling grating 203 includes a first diffraction region 204. By setting the shape of the subwavelength optical structure 206 of at least two basic unit elements 205 of the first diffraction region 24 to be the same, and setting the angle α between the rotation axis L of the at least two basic unit elements 205 and the same period direction to be different, energy loss is reduced, energy utilization is improved and the uniformity of the display field of view is enhanced.

[0067] In some embodiments, at least one periodic direction includes a first periodic direction. In the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of at least two basic unit elements 205 and the first periodic direction is different. The aforementioned first periodic direction can be either the X-axis periodic direction or the Y-axis periodic direction.

[0068] like Figure 6 As shown, the first periodic direction can be the X-axis periodic direction. In the X-axis periodic direction, the angle α between the rotation axis L of at least two basic unit elements 205's subwavelength optical structures 206 and the X-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the X-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0069] In some other embodiments, the first periodic direction may be the Y-axis periodic direction. In the Y-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of at least two basic unit elements 205 and the Y-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the Y-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0070] In some embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit cells 205 and the first periodic direction is different. The first periodic direction can be either the X-axis periodic direction or the Y-axis periodic direction.

[0071] like Figure 6As shown, the first periodic direction can be the X-axis periodic direction. In the X-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit cells 205 and the X-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the X-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0072] In some other embodiments, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit cells 205 and the Y-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the Y-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0073] In some embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the plurality of basic unit elements 205 and the first periodic direction gradually changes sequentially in the first periodic direction. The aforementioned first periodic direction can be the X-axis periodic direction or the Y-axis periodic direction.

[0074] like Figure 6 As shown, the first periodic direction can be the X-axis periodic direction. Along the X-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the multiple basic unit elements 205 and the X-axis periodic direction gradually changes sequentially. This configuration allows for the control of the energy distribution of the first diffraction region 204 along the X-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0075] In some other embodiments, the angle α between the rotation axis L of the subwavelength optical structure 206 of the multiple basic unit elements 205 and the Y-axis periodic direction gradually changes sequentially in the Y-axis periodic direction. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the Y-axis periodic direction, reducing energy loss and improving energy utilization and display field uniformity.

[0076] In some embodiments, at least one periodic direction includes a second periodic direction intersecting the first periodic direction. In the first periodic direction, the angle α between the rotation axes L of the subwavelength optical structures 206 of at least two basic unit elements 205 and the first periodic direction is different. And in the second periodic direction, the angle α between the rotation axes L of the subwavelength optical structures 206 of at least two basic unit elements 205 and the second periodic direction is different. The first periodic direction can be either an X-axis periodic direction or a Y-axis periodic direction.

[0077] like Figure 7As shown, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In the X-axis periodic direction, the angle α between the rotation axis L of at least two basic unit elements 205's subwavelength optical structures 206 and the X-axis periodic direction is different. Similarly, in the Y-axis periodic direction, the angle α between the rotation axis L of at least two basic unit elements 205's subwavelength optical structures 206 and the Y-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the X-axis and Y-axis periodic directions, reducing energy loss and improving energy utilization and display field uniformity.

[0078] In some other embodiments, in the first periodic direction, the angle α between the rotation axis L of at least two basic unit elements 205's subwavelength optical structures 206 and the first periodic direction is different. And in the second periodic direction, the angle α between the rotation axis of the multiple basic unit elements 205's subwavelength optical structures 206 and the second periodic direction remains unchanged. In this embodiment, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In other embodiments, the first periodic direction can be the Y-axis periodic direction, and the second periodic direction can be the X-axis periodic direction.

[0079] In some embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit elements 205 and the first periodic direction is different. Furthermore, in the second periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit elements 205 and the second periodic direction is different. The aforementioned first periodic direction can be either the X-axis periodic direction or the Y-axis periodic direction.

[0080] like Figure 7 As shown, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In the X-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit elements 205 and the X-axis periodic direction is different. Similarly, in the Y-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of two adjacent basic unit elements 205 and the Y-axis periodic direction is different. This configuration allows for the control of the energy distribution of the first diffraction region 204 in the X-axis and Y-axis periodic directions, reducing energy loss and improving energy utilization and display field uniformity.

[0081] In some other embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structures 206 of two adjacent basic unit elements 205 and the first periodic direction is different. Furthermore, in the second periodic direction, the angle α between the rotation axis of the subwavelength optical structures 206 of the plurality of basic unit elements 205 and the second periodic direction remains unchanged. In this embodiment, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In other embodiments, the first periodic direction can be the Y-axis periodic direction, and the second periodic direction can be the X-axis periodic direction.

[0082] In some embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the plurality of basic unit elements 205 and the first periodic direction gradually changes sequentially in the first periodic direction. Furthermore, in the second periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the plurality of basic unit elements 205 and the second periodic direction gradually changes sequentially in the second periodic direction. The aforementioned first periodic direction can be either the X-axis periodic direction or the Y-axis periodic direction.

[0083] like Figure 7 As shown, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In the X-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the multiple basic unit elements 205 and the X-axis periodic direction gradually changes sequentially. Similarly, in the Y-axis periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the multiple basic unit elements 205 and the Y-axis periodic direction gradually changes sequentially. This configuration allows for the control of the energy distribution of the first diffraction region 204 in both the X-axis and Y-axis periodic directions, reducing energy loss and improving energy utilization and display field uniformity.

[0084] In some other embodiments, in the first periodic direction, the angle α between the rotation axis L of the subwavelength optical structure 206 of the plurality of basic unit elements 205 and the first periodic direction gradually changes sequentially in the first periodic direction. And in the second periodic direction, the angle α between the rotation axis of the subwavelength optical structure 206 of the plurality of basic unit elements 205 and the second periodic direction remains unchanged. In this embodiment, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In other embodiments, the first periodic direction can be the Y-axis periodic direction, and the second periodic direction can be the X-axis periodic direction.

[0085] In some embodiments, a plurality of basic unit cells 205 within the first diffraction region 204 are arranged in an odd-symmetric manner with respect to at least one axis of symmetry, the at least one axis of symmetry being parallel to at least one periodic direction. The at least one periodic direction includes a first periodic direction and a second periodic direction; the first periodic direction may be the X-axis periodic direction, and the second periodic direction may be the Y-axis periodic direction. The at least one axis of symmetry is parallel to either the X-axis periodic direction or the Y-axis periodic direction.

[0086] like Figure 8 As shown, at least one axis of symmetry includes a first axis of symmetry and a second axis of symmetry. The first axis of symmetry is parallel to the periodic direction of the X-axis, and the second axis of symmetry is parallel to the periodic direction of the Y-axis. Multiple basic unit elements 205 within the first diffraction region 204 are arranged in an odd-symmetric manner with respect to the first axis of symmetry (parallel to the periodic direction of the X-axis). The multiple basic unit elements 205 within the first diffraction region 204 are also arranged in an odd-symmetric manner with respect to the second axis of symmetry (parallel to the periodic direction of the Y-axis). This arrangement allows for the regulation of energy distribution within the first diffraction region 204 in the periodic directions parallel to the X-axis and Y-axis, reducing energy loss and improving energy utilization and display field-of-view uniformity. Furthermore, by modulating the ratio of energy diffracted towards the central region of the coupling grating 203 to energy diffracted towards the outer region of the coupling grating 203, higher diffraction efficiency can be achieved. This also effectively increases the amount of light diffracted from the coupling grating 203, which is farther from the coupling optical element 202, entering the human eye, thereby effectively improving the visual uniformity of the viewer across the entire field of view.

[0087] In some embodiments, the plurality of basic unit cells 205 of the first diffraction region 204 are arranged in an even-symmetric manner with respect to at least one axis of symmetry, the at least one axis of symmetry being parallel to at least one periodic direction. The at least one periodic direction includes a first periodic direction and a second periodic direction; the first periodic direction may be the X-axis periodic direction, and the second periodic direction may be the Y-axis periodic direction. The at least one axis of symmetry is parallel to either the X-axis periodic direction or the Y-axis periodic direction.

[0088] like Figure 9As shown, at least one axis of symmetry includes a first axis of symmetry and a second axis of symmetry. The first axis of symmetry is parallel to the periodic direction of the X-axis, and the second axis of symmetry is parallel to the periodic direction of the Y-axis. Multiple basic unit elements 205 within the first diffraction region 204 are arranged in an even-symmetric manner with respect to the first axis of symmetry (parallel to the periodic direction of the X-axis). The multiple basic unit elements 205 within the first diffraction region 204 are also arranged in an even-symmetric manner with respect to the second axis of symmetry (parallel to the periodic direction of the Y-axis). This arrangement allows for the regulation of energy distribution along the periodic directions of the X-axis and Y-axis within the first diffraction region 204, reducing energy loss and improving energy utilization and display field-of-view uniformity. Furthermore, by modulating the ratio of energy diffracted towards the central region of the coupling grating 203 to energy diffracted towards the outer region of the coupling grating 203, higher diffraction efficiency can be achieved. This also effectively increases the amount of light diffracted from the coupling grating 203, which is farther from the coupling optical element 202, entering the human eye, thus effectively improving the visual uniformity for the viewer across the entire field of view.

[0089] In some embodiments, a plurality of basic unit cells 205 within the first diffraction region 204 are arranged in a centrally symmetrical manner with respect to at least one symmetrical point within the first diffraction region 204. For example... Figure 8 As shown, the first diffraction region 204 includes a symmetrical point, which is the center point of the first diffraction region 204. Figure 8 In the illustrated embodiment, the plurality of basic unit elements 205 within the first diffraction region 204 are arranged in a centrally symmetrical manner with respect to the center point of the first diffraction region 204. This arrangement enables higher diffraction efficiency by modulating the ratio of energy diffracted towards the central region of the coupling grating 203 to energy diffracted towards the outer regions of the coupling grating 203. It also effectively increases the amount of light diffracted from the coupling grating 203, which is farther from the coupling optical element 202, entering the human eye, thereby effectively improving the visual uniformity of the viewer across the entire field of view.

[0090] In some embodiments, the rotation axis L of the subwavelength optical structure 206 of a plurality of basic unit elements 205 located on one side of at least one axis of symmetry is the same as or different from the angle α included with the same periodic direction. Figure 8 In the illustrated embodiment, the rotation axis L of the subwavelength optical structure 206 of a plurality of basic unit elements 205 located on one side of at least one axis of symmetry is the same as the angle α between them and the same periodic direction. Figure 9 In the illustrated embodiment, in Figure 8In the illustrated embodiment, the rotation axes L of the subwavelength optical structures 206 of the multiple basic unit elements 205 located on one side of at least one axis of symmetry are at different angles α with the same periodic direction. This arrangement allows for flexible setting of the angles α between the rotation axes L of the multiple basic unit elements 205 and the same periodic direction. This increases design freedom and expands the application scenarios while improving energy efficiency.

[0091] In some embodiments, the planar coordinates of at least two reference points of basic unit elements 205 corresponding to different included angles α in the projection plane have the same functional relationship with the included angle α corresponding to the basic unit element 205. The reference point is any point on the orthographic projection of the subwavelength optical structure 206 of the basic unit element 205 in the projection plane. This configuration allows for finely and addressably controlled energy distribution in the first diffraction region 204 of the optical waveguide's coupling grating 203 throughout the entire field of view, compensating for unavoidable energy distribution non-uniformity caused by differences in the propagation paths of light rays in each field of view, thereby improving the uniformity of energy distribution across the entire field of view.

[0092] In some embodiments, the functional relationship includes a univariate functional relationship. In some embodiments, in the first periodic direction, the included angle α corresponding to at least two basic unit elements 205 is different, and the included angle α corresponding to the at least two basic unit elements 205 has a first univariate functional relationship with the planar coordinates of the corresponding reference point in the first periodic direction. For example... Figure 6 As shown, the first periodic direction can be the X-axis periodic direction. In the X-axis periodic direction, the included angle α corresponding to at least two basic unit elements 205 is different, and the included angle α corresponding to these at least two basic unit elements 205 has a first univariate functional relationship z = f(x) with the planar coordinates of the corresponding reference point in the X-axis periodic direction. In this embodiment, there is no limitation on the Y-axis periodic direction. This configuration allows for finely and addressably controlled energy distribution in the first diffraction region 204 of the optical waveguide's coupling grating 203 within the field of view parallel to the X-axis periodic direction. This compensates for the unavoidable energy distribution non-uniformity caused by differences in the propagation paths of field rays parallel to the X-axis periodic direction within the waveguide, thereby improving the uniformity of the energy distribution across the entire field of view.

[0093] In some other embodiments, in the second periodic direction, the included angle α corresponding to at least two basic unit elements 205 is different, and the included angle α corresponding to the at least two basic unit elements 205 has a second univariate functional relationship with the planar coordinates of the corresponding reference point in the second periodic direction. The second periodic direction can be the Y-axis periodic direction. In the Y-axis periodic direction, the included angle α corresponding to at least two basic unit elements 205 is different, and the included angle α corresponding to the at least two basic unit elements 205 has a second univariate functional relationship z = f(y) with the planar coordinates of the corresponding reference point in the Y-axis periodic direction. In this embodiment, there is no limitation on the X-cycle periodic direction. With this configuration, the energy distribution of the first diffraction region 204 of the optical waveguide's coupling grating 203 in the field of view parallel to the Y-axis periodic direction can be finely and addressably controlled to compensate for the unavoidable energy distribution non-uniformity caused by the difference in the propagation path of the field of view rays parallel to the Y-axis periodic direction, thereby improving the uniformity of the energy distribution across the entire field of view.

[0094] In some embodiments, the functional relationship includes a binary functional relationship. In some embodiments, at least two basic unit elements 205 have different included angles α in the first periodic direction, and at least two basic unit elements 205 have different included angles α in the second periodic direction. In the plane formed by axes parallel to the first periodic direction and parallel to the second periodic direction, the included angles α of these corresponding basic unit elements 205 with different included angles α relative to the same periodic direction and the planar coordinates of the corresponding reference points have a binary functional relationship. Figure 9 As shown, the first periodic direction can be the X-axis periodic direction, and the second periodic direction can be the Y-axis periodic direction. In the X-axis periodic direction, at least two basic unit elements 205 have different included angles α, and in the Y-axis periodic direction, at least two basic unit elements 205 have different included angles α. On axes parallel to the X-axis and Y-axis periodic directions, the included angles α of these basic unit elements 205 with different included angles α relative to the same periodic direction, and the planar coordinates of the corresponding reference points, have a bivariate functional relationship z = f(x,y).

[0095] In some embodiments, the bivariate functional relationship z = f(x, y) is relative to the straight line y = y parallel to the periodic direction of the X-axis. P Assuming odd symmetry, i.e., z = f(x, y) satisfies the relation f(x, yy). P )+f(x,-y+y P ) = 0. In other embodiments, the bivariate functional relationship z = f(x, y) is relative to the straight line x = x parallel to the periodic direction of the Y-axis. Q For even-symmetric settings, i.e., z = f(x,y) satisfies the relation f(xx) Q ,y)-f(-x+xQ In some other embodiments, the bivariate functional relation z = f(x, y) is relative to any point (x, y) in the two-dimensional plane. C ,y C The setting is centrally symmetric, that is, z = f(x,y) satisfies the relation f(xx). C ,y)-f(-x+x C f(x,y)=0 and f(x,yy)=0 C )+f(x,-y+y C ) = 0.

[0096] In some embodiments, the bivariate functional relationship z = f(x,y) is a periodic function along the periodic direction of the X-axis and / or the periodic direction of the Y-axis, that is, z = f(x,y) satisfies the relationship f(x+T) x f(x,y) = f(x,y) and / or f(x,y+T) y ) = f(x,y), where T x and T y Let z = f(x,y) be the periodicity of the function along the X-axis and Y-axis. It should be noted that the periodicity and parity of the bivariate function z = f(x,y) can coexist.

[0097] In some embodiments, the functional relationship is a piecewise functional relationship. The bivariate functional relationship z = f(x,y) is a piecewise functional relationship along the periodic direction of the X-axis and / or the periodic direction of the Y-axis. It should be noted that the piecewise property and parity of the bivariate functional relationship z = f(x,y) can coexist, and the piecewise function can also have periodicity within any domain segment.

[0098] In some embodiments, the functional relationship is a distribution function relationship. The bivariate functional relationship z = f(x,y) is a distribution function relationship along the periodic X-axis and / or Y-axis. In some embodiments, the distribution function relationship includes one-dimensional or two-dimensional distribution functions, such as the Bessel distribution function, Green's distribution function, Poisson distribution function, chi-square distribution function, binomial distribution function, step distribution function, and other continuous or discrete distribution functions, symmetric or asymmetric distribution functions. This application does not impose any limitations.

[0099] In some embodiments, the bivariate functional relationship includes a first quasi-univariate functional relationship z = f(x0, y) in the planar coordinates along the second periodic direction (the periodic direction of the Y-axis), where x0 is an arbitrary or constant value. Furthermore, the first quasi-univariate functional relationship z = f(x0, y) is relative to the straight line y = y' parallel to the periodic direction of the X-axis. P Assuming odd symmetry, i.e., z = f(x, y) satisfies the relation f(x, yy). P )+f(x,-y+y P ) = 0.

[0100] In some embodiments, the bivariate functional relationship includes a second quasi-univariate functional relationship z = f(x, y0) in planar coordinates along the first periodic direction (the periodic direction of the X-axis), where y0 is an arbitrary or constant value. Furthermore, the second quasi-univariate functional relationship z = f(x, y0) is relative to a straight line x = x parallel to the periodic direction of the Y-axis. Q For even-symmetric settings, i.e., z = f(x, y0) satisfies the relation f(xx). Q ,y0)-f(-x+x Q ,y0)=0.

[0101] This configuration allows for precise and addressable control of the energy distribution within the field of view of the first diffraction region 204 of the optical waveguide's coupling grating 203 along the axes parallel to the X-axis and Y-axis periodic directions. This compensates for the unavoidable energy distribution non-uniformity caused by differences in the propagation paths of light rays along the X-axis and Y-axis periodic directions within the waveguide, thereby improving the uniformity of the energy distribution across the entire field of view. Furthermore, it ensures that when light rays propagating in the optical waveguide are incident on the first diffraction region 204 to couple out display light and expand the two-dimensional exit pupil, more energy is confined within the first diffraction region 204, preventing excessive light leakage from its edges and thus improving the energy utilization rate of the optical waveguide.

[0102] exist Figure 8 In the illustrated embodiment, the coupling optical element 202 is circular. The coupling grating 203 includes a first diffraction region 204, the outline of which is rectangular. When the display image in the projection optical engine illuminates the coupling optical element 202, the coupling optical element 202 can impart an additional wave vector to the incident light, causing the light to enter the near-eye display waveguide 200. Subsequently, the light in the near-eye display waveguide 200 is transmitted efficiently and without loss through total internal reflection from the direction of the coupling optical element 202 to the direction of the coupling grating 203. When the light illuminates the coupling grating 203, part of the energy is coupled out of the near-eye display waveguide 200 and enters the human eye to realize the near-eye display function, while part of the energy continues to be transmitted forward and dispersed to both sides to realize two-dimensional exit pupil expansion.

[0103] exist Figure 8In the illustrated embodiment, the waveguide substrate 201 is optical glass with a refractive index between 1.40 and 2.30. The basic unit cells 205 periodically arranged on the waveguide substrate 201 are the rhomboid regions circled by the double-dotted lines in the figure. These basic rhomboid regions are uniformly and periodically arranged without overlap or gaps on the surface of the waveguide substrate 201 along two periodic directions (X-axis and Y-axis), thus forming the first diffraction region 204. Each basic unit cell 205 in the first diffraction region 204 contains a rhomboid subwavelength optical structure 206 made of resin with a refractive index similar to that of the waveguide substrate. This rhomboid subwavelength optical structure 206 has two axes of symmetry, namely the major axis and the minor axis of the rhomboid structure. Figure 8 The embodiment shown selects its major axis as the rotation axis L of the subwavelength optical structure 206, and the rhomboid subwavelength optical structure 206 is mirror-symmetrically arranged with respect to this rotation axis L. For example... Figure 8 As shown, the rotation axis L is set at an angle α with the periodic direction of the X-axis. When the angle α expands counterclockwise relative to the periodic direction of the X-axis, its value is defined as positive; when the angle α expands clockwise relative to the periodic direction of the X-axis, its value is defined as negative. Thus, the range of the angle α is determined to be (-π, π).

[0104] exist Figure 8 In the illustrated embodiment, the angle α between the rotation axis L of the subwavelength optical structure 206 and the periodic X-axis direction of the basic unit element 205 arranged on the surface of the waveguide substrate 201, and the plane coordinates (x, y) of the subwavelength optical structure 206, has a bivariate functional relationship z = f(x, y). The expression for the bivariate functional relationship z = f(x, y) is:

[0105]

[0106] Here, α0 is a specific angle value; the domain of the planar coordinates (x, y) is the maximum coverage area of ​​the first diffraction region 204. Simultaneously, z = f(x, y) is odd-symmetric relative to the line y = 0 parallel to the X-axis periodic direction in the plane of the waveguide substrate 201, meaning z = f(x, y) satisfies the relationship f(x, y) + f(x, -y) = 0. Furthermore, z = f(x, y) is also odd-symmetric relative to the line x = 0 parallel to the Y-axis periodic direction in the plane of the waveguide substrate 201, meaning z = f(x, y) satisfies the relationship f(x, y) + f(-x, y) = 0.

[0107] use Figure 8The near-eye display waveguide 200 of the embodiment shown can achieve high diffraction efficiency by modulating the ratio of energy diffracted to the central region of the coupling grating 203 and energy diffracted to the outer region of the coupling grating 203. It can also effectively improve the light diffracted into the human eye from the coupling region which is far from the coupling optical element 202, thereby effectively improving the visual uniformity of the viewer in the entire field of view.

[0108] exist Figure 9 In the illustrated embodiment, the angle α between the rotation axis L of the subwavelength optical structure 206 and the periodic X-axis direction of the basic unit element 205 arranged on the surface of the waveguide substrate 201 has a bivariate functional relationship z = f(x,y) with respect to the plane coordinates (x,y) of the subwavelength optical structure 206, and z = f(x,y) has a piecewise function property in the periodic Y-axis direction. The expression for the piecewise function f(x,y) is:

[0109]

[0110] Where g(x,y) is a linear distribution function along the periodic direction of the Y-axis, and its expression is:

[0111] g(x, y) = |ax + b|;

[0112] Wherein, the domain of the plane coordinates (x, y) is the maximum coverage of the first diffraction region 204; a and b are linear distribution coefficients, which satisfy the inequality condition 0 ≤ g(x, y) ≤ 1 (when y takes any value); α0 is a specific angle value, in this embodiment α0 = π / 6; y0 is the segmented interval of the piecewise function, and its value range is smaller than the maximum coverage of the first diffraction region 204.

[0113] In some other implementations, g(x,y) can be a planar Gaussian distribution function, with the expression:

[0114]

[0115] The domain of the plane coordinates (x, y) is the maximum coverage of the first diffraction region 204; a and b are Gaussian-like distribution coefficients, which satisfy the inequality condition 0 ≤ g(x, y) ≤ 1 (when y takes any value).

[0116] In some embodiments, g(x,y) may also be other one-dimensional or two-dimensional distribution functions, such as Bessel distribution function, Green distribution function, Poisson distribution function, chi-square distribution function, binomial distribution function, step distribution function, etc., which are continuous or discrete distribution functions, symmetric or asymmetric distribution functions.

[0117] In some embodiments, the first diffraction region 204 includes at least one sub-diffraction region. For example... Figure 10 As shown, the first diffraction region 204 includes a first sub-diffraction region 2041 and a second sub-diffraction region 2042. The rotation axes L of the subwavelength optical structures 206 of the multiple basic unit elements 205 in the first sub-diffraction region 2041 are at the same angle α with respect to the same periodic direction. Similarly, the rotation axes L of the subwavelength optical structures 206 of the multiple basic unit elements 205 in the second sub-diffraction region 2042 are at the same angle α with respect to the same periodic direction. However, the angles α between the multiple basic unit elements 205 in the first sub-diffraction region 2041 and the multiple basic unit elements 205 in the second sub-diffraction region 2042 and the corresponding elements with respect to the same periodic direction are different.

[0118] In some embodiments, the first sub-diffraction region 2041 and the second sub-diffraction region 2042 are symmetrically arranged with respect to a region symmetry axis. This region symmetry axis is parallel to a periodic direction. Specifically, the region symmetry axis is the axis of symmetry between the first sub-diffraction region 2041 and the second sub-diffraction region 2042. Figure 10 In the illustrated embodiment, the axis of symmetry of this region is parallel to the periodic direction of the X-axis. In some other embodiments, the axis of symmetry of this region is parallel to the periodic direction of the Y-axis.

[0119] exist Figure 10 In the illustrated embodiment, the angle α between the rotation axis L of the subwavelength optical structure 206 and the X-axis periodic direction of the basic unit element 205 arranged on the surface of the waveguide substrate 201 has a quasi-univariate functional relationship z = f(x0,y) with respect to the linear coordinate y along the Y-axis periodic direction, where x0 is an arbitrary constant or fixed value. The expression for the function f(x0,y) is:

[0120]

[0121] Wherein, α0 is a specific angle value; the domain of the linear coordinate y is the maximum coverage of the first diffraction region 204; and z = f(x0,y) is odd symmetric relative to the line y = 0 parallel to the X-axis periodic direction in the plane of the waveguide substrate 201, that is, z = f(x0,y) satisfies the relationship f(x0,y) + f(x0,-y) = 0.

[0122] use Figure 10 The near-eye display waveguide 200 of the illustrated embodiment, when light from the near-eye display waveguide 200 illuminates the coupling grating 203 to achieve two-dimensional exit pupil expansion, can effectively modulate the ratio of energy diffracted towards the central region of the coupling grating 203 to the energy diffracted towards the outer region of the coupling grating 203. When the ratio reaches its maximum value, the near-eye display waveguide 200 achieves the highest diffraction efficiency and the maximum energy utilization rate, thereby allowing more energy to enter the human eye through the coupling grating 203, thus providing the viewer with higher visual brightness.

[0123] In some embodiments, the coupling grating 203 further includes a second diffraction region 207, which includes diffraction unit elements 208 arranged in at least one arrangement direction. The subwavelength optical structures 209 or groups of subwavelength optical structures (multiple subwavelength optical structures 209) of the diffraction unit elements 208 of the second diffraction region 207 may have the same or different shapes as the subwavelength optical structures 206 of the basic unit element 205 of the first diffraction region 204. The rotation axes of the subwavelength optical structures 209 or groups of subwavelength optical structures (multiple subwavelength optical structures 209) of the diffraction unit elements 208 of the second diffraction region 207 are at the same angle α with the same arrangement direction. Figure 10 In the illustrated embodiment, the subwavelength optical structure 209 or group of subwavelength optical structures (multiple subwavelength optical structures 209) of the diffraction unit 208 of the second diffraction region 207 has the same shape as the subwavelength optical structure 206 of the basic unit 205 of the first diffraction region 204. In other embodiments, the subwavelength optical structure 209 or group of subwavelength optical structures (multiple subwavelength optical structures 209) of the diffraction unit 208 of the second diffraction region 207 has a different shape than the subwavelength optical structure 206 of the basic unit 205 of the first diffraction region 204. This is not a limitation in this application.

[0124] In the above Figures 1 to 10 In the illustrated embodiments, the surface of the waveguide substrate 201 is any one of a plane, a convex surface, a concave surface, an aspherical surface, or a freeform surface. In some embodiments, the waveguide substrate 201 may have various geometric configurations. In some embodiments, the waveguide substrate 201 may have a refractive index distribution, with the refractive index value ranging from 1.40 to 2.30. In some embodiments, the material of the waveguide substrate 201 may be one or a combination of optical glass, optical resin, and optical glass-resin materials.

[0125] In some embodiments, the first diffraction region 204 is a regular or irregular region enclosed by straight edges, curved edges, or both straight and curved edges. In some embodiments, the first diffraction region 204 is rectangular, pentagonal, hexagonal, or circular, and is not limited thereto. In some embodiments, the refractive index values ​​of the subwavelength optical structures 206 at different coordinate positions in the first diffraction region 204 may be the same or different. In some embodiments, the coupling grating 203 further includes other diffraction regions, which may be composed of one-dimensional and / or two-dimensional straight-tooth gratings, blazed gratings, or tilted gratings. In other embodiments, the other diffraction regions may also be composed of photonic crystals, metamaterials, or metasurfaces.

[0126] In some embodiments, the basic unit element 205 can be a closed structural region formed by a combination of straight lines and / or curves. If the arrangement of the basic unit elements 205 on the surface of the waveguide substrate 201 has only one periodic direction, as a preferred embodiment, the region outline of the basic unit element 205 is rectangular (e.g., ...). Figure 6 (As shown). If the arrangement of the basic unit element 205 on the surface of the waveguide substrate 201 has two periodic directions, as a preferred embodiment, the region profile of the basic unit element 205 is rectangular or rhomboid (e.g., Figures 7 to 10 (As shown). When the region outline of the basic unit element 205 is a rhombus, the non-obtuse angle of the rhombus is equal to the non-obtuse angle between the first period direction and the second period direction.

[0127] In some embodiments, when the arrangement of the basic unit cells 205 on the surface of the waveguide substrate 201 has a first periodic direction and a second periodic direction, as a preferred embodiment, the included angle α between the first periodic direction and the second periodic direction is ±π / 3 or ±π / 2. For the same arrangement of basic unit cells 205 on the surface of the waveguide substrate 201, the first periodic direction and the second periodic direction can be defined as different directions according to their two-dimensional planar periodic characteristics, and therefore the included angle α between them can have different values, but they are always parallel to and intersect the plane where the waveguide substrate is located.

[0128] In some embodiments, the subwavelength optical structure 206 is a symmetrical structure. Furthermore, the subwavelength optical structures 206 of adjacent basic unit cells 205 have the same geometry and dimensions. Compared to related technologies, the regular and symmetrical subwavelength optical structure 206 of this application allows for direct design optimization based on the existing optical structure configuration, significantly reducing the computational and time costs of design iterations. Moreover, it can be directly delivered for production without additional process iterations based on the existing nanoimprint processing technology, offering significant economic benefits and mass production advantages.

[0129] In some embodiments, the subwavelength optical structure 206 includes a columnar structure, a conical structure, or a frustum structure. In some embodiments, the cross-section of the subwavelength optical structure 206 is a regular shape formed by straight edges, or by curved edges, or by both straight and curved edges. This subwavelength optical structure 206 is a closed optical structure. Figures 6 to 10 In the illustrated embodiment, the subwavelength optical structure 206 is a rhomboid subwavelength optical structure. This configuration allows for flexible adjustment of the light response capability and improves the uniformity of the field of view. This application does not impose limitations on this design.

[0130] In some embodiments, a gap exists between the subwavelength optical structures 206 of adjacent basic unit cells 205. Electromagnetic interaction occurs between the subwavelength optical structures 206 and the gaps, allowing arbitrary control over the phase, amplitude, and polarization state of the incident light, resulting in highly flexible optical response and improved field-of-view uniformity and energy utilization. In some embodiments, the gap may contain air or an inert gas with a refractive index near 1.00. In some embodiments, the gap is filled entirely with air or an inert gas. In some special applications, the gap may also contain a liquid with a refractive index slightly greater than 1.00. However, the refractive index at the gap differs from that of the subwavelength optical structure 206. In some embodiments, the gap may be filled with a dielectric structure with a refractive index between 1.40 and 2.30. This configuration allows for flexible adjustment of the field-of-view uniformity of the coupling grating 203.

[0131] In some embodiments, the height of the subwavelength optical structure 206 ranges from 10 nm to 850 nm. In other embodiments, the height of the subwavelength optical structure 206 ranges from 10 nm to 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, or 850 nm. When the height of the subwavelength optical structure 206 is within the range of 10 nm to 850 nm, significant electromagnetic interactions can form at the gaps between adjacent subwavelength optical structures 206, thereby affecting the electromagnetic response of the coupling grating 203. Simultaneously, within this height range of the subwavelength optical structure 206, the coupling grating 203, periodically arranged from basic unit elements 205, can all achieve the function of two-dimensional exit pupil expansion.

[0132] In some embodiments, the total area of ​​the subwavelength optical structure 206 within the basic unit element 205 does not exceed the area of ​​the basic unit element 205. In some embodiments, the total area (excluding gaps) of the subwavelength optical structure 206 within the basic unit element 205 is 0.4 to 1.0 of the area of ​​the basic unit element 205. This is not limited in this application.

[0133] In some embodiments, the subwavelength optical structure 206 may have a refractive index distribution. The subwavelength optical structure 206 may be one or a combination of optical glass, optical resin, and optical glass-resin materials, with a refractive index between 1.40 and 2.30. In some embodiments, the refractive index of the subwavelength optical structure 206 may be the same as or different from the refractive index of the waveguide substrate 201.

[0134] In some embodiments, the subwavelength optical structure 206 and / or its gaps are subwavelength dielectric structures with surface relief characteristics, which can be fabricated on the surface of the waveguide substrate with high precision, low cost and large area by nanoimprinting process.

[0135] In some embodiments, the waveguide substrate can have various geometric configurations. In some embodiments, the waveguide substrate is a planar lens; in some embodiments, the waveguide substrate can be a convex lens, a concave lens, an aspherical lens, or a freeform surface lens, or a combination of the above lenses.

[0136] In some embodiments, the surface of the subwavelength optical structure of the basic unit element 205 is provided with an optical coating or plating. In some embodiments, the material of the optical coating or plating may be a metallic material, a dielectric material, and / or a composite material composed of a metal and a dielectric. In some embodiments, the material of the optical coating or plating is one or a combination of at least two of silicon dioxide, aluminum oxide, titanium dioxide, tantalum pentoxide, hafnium oxide, and zirconium oxide. In some embodiments, the thickness of the optical film or coating of each material is less than the operating wavelength of the optical waveguide device. This configuration allows for control of the diffraction efficiency of the coupling grating 203 and improvement of energy utilization through coating or plating, and also effectively alters the ratio of transmitted and reflected light energy entering the human eye 300.

[0137] In the above scheme, the near-eye display device 10 includes the above-mentioned Figures 6 to 10 The near-eye display waveguide 200 shown in the embodiment can improve near-eye display performance. Figure 11 The figure shown is a simulation diagram of the energy distribution in the display field of a near-eye display device of a related technology. Figure 12 As shown Figure 5 The diagram shown is a simulation of the energy distribution in the field of view displayed by the near-eye display device. See also... Figure 11 and Figure 12 As shown, Figure 12 The grayscale values ​​represent the light intensity distribution perceived by a user when viewing the entire display field of view. Lighter areas are perceived as brighter by the user, while darker areas are perceived as darker. For the near-eye display device 10 made using the near-eye display waveguide 200 of this application embodiment, Figure 12 The coupling energy within the field of view inside the dashed frame is increased, thereby significantly improving the display brightness perceived by the user when viewing the corresponding area. Therefore, the near-eye display device 10 made using the near-eye display waveguide 200 disclosed in this embodiment of the invention has higher application value in high-brightness environments such as outdoors.

[0138] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A near-eye display optical waveguide, characterized in that, include: The system comprises a waveguide substrate, at least one coupling optical element, and at least one coupling grating. The coupling optical element and the coupling grating are disposed on the waveguide substrate, and the coupling grating and the waveguide substrate are stacked in a stacking direction. The coupling optical element is used to couple a light beam into the waveguide substrate. The coupling grating is used to couple the light beam out of the waveguide substrate. The coupling grating includes a first diffraction region comprising a plurality of basic unit elements periodically arranged in at least one periodic direction parallel to the waveguide substrate. Each basic unit element includes at least one subwavelength optical structure, and at least two of the basic unit elements in the first diffraction region have subwavelength optical structures of identical shape. When the basic unit cell includes at least two subwavelength optical structures, the rotation axes of each subwavelength optical structure within the same basic unit cell are at the same angle to the periodic direction; the rotation axes of the subwavelength optical structures between different basic units cell are at completely different angles to the periodic direction. Alternatively, when the basic unit element includes at least two subwavelength optical structures, the rotation axes of the subwavelength optical structures within the same basic unit element have the same angle with the periodic direction; the rotation axes of the subwavelength optical structures between the basic units element have not the same angle with the periodic direction. Alternatively, if the basic unit has only one subwavelength optical structure, the angles between the rotation axes of the subwavelength optical structures of each basic unit and the periodic direction are either completely different or not completely the same. The subwavelength optical structure has at least one axis of symmetry, the cross-sectional shape of which is mirror-symmetric or anti-symmetric with respect to the axis of symmetry, and the axis of symmetry is defined as a rotation axis.

2. The near-eye display waveguide according to claim 1, characterized in that, The at least one periodic direction includes a first periodic direction in which the angle between the rotation axis of the subwavelength optical structure of at least two of the basic unit elements and the first periodic direction is different.

3. The near-eye display waveguide according to claim 2, characterized in that, In the first periodic direction, the angle between the rotation axis of the subwavelength optical structure of two adjacent basic units and the first periodic direction is different.

4. The near-eye display waveguide according to claim 3, characterized in that, In the first periodic direction, the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the first periodic direction gradually changes sequentially in the first periodic direction.

5. The near-eye display waveguide according to any one of claims 2-4, characterized in that, The at least one periodic direction includes a second periodic direction that intersects the first periodic direction, wherein the angle between the rotation axis of the subwavelength optical structure of at least two of the basic unit elements and the second periodic direction is different.

6. The near-eye display waveguide according to claim 5, characterized in that, In the second periodic direction, the angle between the rotation axis of the subwavelength optical structure of two adjacent basic units and the second periodic direction is different.

7. The near-eye display waveguide according to claim 6, characterized in that, In the second periodic direction, the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the second periodic direction gradually changes sequentially in the second periodic direction.

8. The near-eye display waveguide according to any one of claims 2-4, characterized in that, The at least one periodic direction includes a second periodic direction, in which the angle between the rotation axis of the subwavelength optical structure of the plurality of basic unit elements and the second periodic direction remains unchanged.

9. The near-eye display waveguide according to claim 1, characterized in that, The plurality of basic unit elements in the first diffraction region are arranged in an odd-symmetric or even-symmetric manner with respect to at least one axis of symmetry, wherein the at least one axis of symmetry is parallel to the at least one periodic direction.

10. The near-eye display waveguide according to claim 9, characterized in that, The rotation axes of the subwavelength optical structures of the plurality of basic unit elements located on one side of the at least one axis of symmetry may be the same or different from the angles between them and the same periodic direction.

11. The near-eye display waveguide according to claim 1, characterized in that, The plurality of basic unit elements in the first diffraction region are arranged in a centrally symmetrical manner with respect to at least one symmetrical point in the first diffraction region.

12. The near-eye display waveguide according to claim 1, characterized in that, The planar coordinates of at least two reference points of the basic unit element corresponding to different included angles in the projection plane have the same functional relationship with the included angle corresponding to the basic unit element. The reference point is any point on the orthographic projection of the subwavelength optical structure of the basic unit element in the projection plane.

13. The near-eye display waveguide according to claim 12, characterized in that, The at least one periodic direction includes a first periodic direction, in which the included angles corresponding to at least two of the basic unit elements are different, and the included angles corresponding to the at least two of the basic unit elements have a first univariate functional relationship with the planar coordinates of the corresponding reference point in the first periodic direction.

14. The near-eye display waveguide according to claim 13, characterized in that, The at least one periodic direction includes a second periodic direction that intersects with the first periodic direction. In the second periodic direction, the included angles corresponding to at least two of the basic unit elements are different, and the included angles corresponding to the at least two of the basic unit elements have a second univariate functional relationship with the planar coordinates of the corresponding reference point in the second periodic direction.

15. The near-eye display waveguide according to claim 12, characterized in that, The at least one periodic direction includes a first periodic direction and a second periodic direction intersecting the first periodic direction. In the first periodic direction, the included angles corresponding to at least two of the basic unit elements are different. In the second periodic direction, the included angles corresponding to at least two of the basic unit elements are different. In the plane formed by axes parallel to the first periodic direction and parallel to the second periodic direction, the angles of the corresponding basic unit elements with different included angles relative to the same periodic direction and the plane coordinates of the corresponding reference points have a binary function relationship.

16. The near-eye display optical waveguide according to claim 12, characterized in that, The functional relationship is a distributed functional relationship or a piecewise functional relationship.

17. The near-eye display waveguide according to claim 1, characterized in that, The subwavelength optical structure is a symmetrical structure; and / or The subwavelength optical structure includes a columnar structure, a conical structure, or a truncated structure; and / or The cross-section of the subwavelength optical structure is a regular shape formed by straight edges, or by curved edges, or by both straight and curved edges; and / or The surface of the waveguide substrate is any one of a plane, a convex surface, a concave surface, or a freeform surface; and / or The first diffraction region is a regular or irregular region enclosed by straight edges, or by curved edges, or by both straight and curved edges.

18. The near-eye display waveguide according to claim 1, characterized in that, The coupling grating further includes a second diffraction region, which includes diffraction unit elements arranged in at least one arrangement direction. The subwavelength optical structure of the diffraction unit elements in the second diffraction region has the same or different shape as the subwavelength optical structure of the basic unit element in the first diffraction region. The rotation axis of the subwavelength optical structure of the diffraction unit elements in the second diffraction region is at the same angle to the same arrangement direction.

19. The near-eye display waveguide according to claim 1, characterized in that, The first diffraction region includes a first sub-diffraction region and a second sub-diffraction region, wherein the rotation axis of the subwavelength optical structure of the plurality of basic unit elements in the first sub-diffraction region is the same as the angle between the rotation axis and the same periodic direction. The rotation axes of the subwavelength optical structures of the plurality of basic units in the second sub-diffraction region are at the same angle with respect to the same periodic direction; the angles of the plurality of basic units in the first sub-diffraction region and the plurality of basic units in the second sub-diffraction region relative to the same periodic direction are different.

20. The near-eye display waveguide according to claim 19, characterized in that, The first sub-diffraction region and the second sub-diffraction region are symmetrically arranged with respect to a regional axis of symmetry, which is parallel to one of the periodic directions, wherein the regional axis of symmetry is the axis of symmetry between the first sub-diffraction region and the second sub-diffraction region.

21. A near-eye display device, characterized in that, include: Projection device; and The near-eye display waveguide according to any one of claims 1 to 20, wherein the projection device is disposed on one side of the waveguide; The coupling optical element of the optical waveguide is used to couple the light beam containing image information emitted by the projection device to the waveguide substrate of the optical waveguide.

Images